++ . , , , ; ++.
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++ , ios sterambuf. ios , steambuf .
:
ios ;
istream ;
ostream ;
iostream ;
istringstream ;
ostringstream ;
stringstream ;
ifstream ;
ofstream ;
fstream .
:
<ios> /;
<iosfwd> /;
<istream> ;
|
|
|
<ostream> ;
<iostream> /;
<fstream> / ;
<sstream> / ;
<streambuf> /;
<iomanip> (. ).
<iostream> / (.1).
1
| cin | istream | ( ) |
| cout | ostream | ( ) |
.1
| cerr | ostream | ( ), |
| clog | ostream | ( ), |
istream ostream >> << .
( 0x) . ( ).
( 0-).
.
: , .
, x_flags long ios.
2
| skipws | + | |
| left | - | |
| right | + | |
| internal | - | , |
| dec | + | |
| oct | - | |
| hex | - | |
| showbase | - | (0x , 0 ) |
| showpoint | - | |
| uppercase | - | |
| scientific | - | |
| fixed | - |
ios flags, setf unsetf.
long ios:: flags (long); ;
long ios:: flags (long); ;
long ios:: setf (long, long); , , ;
long ios:: setf (long, long); , ;
long ios:: unsetf (long, long); , ;
.
|
|
|
ios:
int x_width ;
int x_precision ;
int x_fill .
width, precision fill:
int ios:: width () ;
int ios:: width () ;
int ios:: precision () ;
int ios:: precision (int) ;
char fill () ;
char fill (char) ( ).
, . setf ios:
adjustfield (left | right | internal)
basefield (dec | oct | hex)
floatfield (scientific | fixed)
# include <iostream.h>
int main () {
long a = 100, b = 077;
cout.width (7); cout.unsetf (ios:: dec);
cout.setf (ios:: hex | ios:: showbase | ios::uppercase);
cout << a;
cout.width (7);
cout << b << endl;
double d = 0.12, c = 1.3e-4;
cout.setf(ios:: left);
cout << d << endl;
cout << c;
return 0;
}
:
0X3T8 0X3F
0.12
0.00013
, . . .
dec ;
oct ;
hex ;
ws ;
endl ;
ends ;
flush .
.
cout << 13 << hex << << 13 << oct << << 13 << endl;
:
13 d 15
, . <iomanip>.
setbase (int n) (n = 8, 10, 16 0). 0 (, , );
resetiosflags (long) , ;
setfill (int) - , ;
setprecision (int) ;
setw (int) ;
setiosflags (long) , 1.
double d (1.234);
cout << setfill (.) << setprecision (4)
<< setiosflags (ios:: showpoint | ios:: fixed);
cout << setw (12) << d << endl;
:
1.2340
>> << ( ).
| istream | |
| gcount () | , |
| get () | EOF |
| get (buf, num, lim = \n) | num-1 ( lim) buf. lim (\0). lim . |
| getline (buf, num, lim = \n) | get (), buf lim |
|
|
|
| ignore (num = 1, lim = EOF) | , num ( 1) lim. |
| peek () | EOF, |
| putback (c) | , |
| read (buf, num) | num ( , num) buf |
| readsome (buf, num) | num buf |
| seekg (pos) | pos |
| seekg (offs, org) | offs , , org: ios:: beg ( ), ios:: cur ( ) ios:: end ( ) |
| tellg () | |
| ostream | |
| flush () | |
| ut () |
| seekg (pos) | pos |
| seek (ofs, org) | offs , (. ) |
| tellg () | |
| write (buf, num) | num buf |
1. .
# include <iostream.h>
int main () {
const int N = 20, Len = 100;
char str [Len] [N]
int i = 0;
while (cin.getline (str [i], Len, \n) & & i < N) {
i ++;}
return 0;
}
2. test, ( . ).
# include <iostream.h>
# include <fstream.h>
# include <string.h>
int main () {
//
ofstream out (test);
if (!out) {
cout << << endl;
return 1;
}
char *str [ ] = {the first line, the second line, the third line};
for (int i = 0; i<3, ++ i) {
out.write (str [i], strlen (str [i]));
out.put (\n);
}
out.close ();
//
ifstream in (test);
if (! in) {
cout << << endl;
return 1;
}
char check_str [3] [30];
for (int i = 0; i < 3; ++ i) {
in.get (check_str [i], 30);
in.get (); }
for (int i = 0; i < 3; ++ i) cout << check_str [i] << endl;
in.close ();
return 0;
}
3. peek () putback ().
, . , . .
# include <iostream.h>
# include <fstream.h>
# include <stdlib>
int main () {
char ch;
//
ofstream out (test);
cout << test << endl;
return1;
}
char str [80], *p;
|
|
|
out << 123 << << 23;
out << << 99 << << endl;
out.close ();
//
ifstream in (test);
if (!in) {
cout << test << endl;
return 1;
}
do {
p = str;
ch = in.peek (); //
if (isdigit(ch)) {
while (isalpha (*p = in.get ())) p ++; //
in.putback (*p); //
* = \0; //
cout << : << atoi (str);
}
else if (isalpha (ch)) { //
while (isalpha (*p = in.get ())) p ++;
in.putback (*p); //
*p = \0; //
cout << : << str;
}
else in.get (); //
cout << endl;
} while (!in.eof ());
in.close ();
return 0;
}
:
: 123
:
:
:
: 23
:
:
: 99
:
ios state, :
enum io_state {
googbit = 0x00, //
eofbit = 0x01, //
failbit = 0x02, //
badbit = 0x04, // ,
//
hardbit = 0x08 //
};
:
int rdstate () ;
int eof () , eofbit;
int fail () , failbit, badbit hardbit;
int good () , ;
void clear (int = 0) , 0;
operator void *() , ;
operator! () , .
. :
// , flag
if (steam_obj.rdstate () & ios:: flag)
// flag
stream_obj.clear (rdstate () & ~ios:: flag)
// flag
stream_obj.clear (rdstate () | ios:: flag)
// flag
stream_obj.clear (ios:: flag)
//
stream_obj.clear ()
void *() , . :
while (stream_obj) {
// , /
}
:
ifstream ;
ofstream ;
fstream .
istream, ostream iostream .
:
- ;
- ;
- (/);
- ;
- .
, .
, :
ifstream ();
ofstream ();
fstream ();
, :
ifstream (const char * name, int mode = ios:: in);
ofstream (const char * name, int mode = ios:: out | ios:: trunc);
fstream (const char * name, int mode = ios:: in | ios:: out);
.
, open, , .
1
ifstream inpf (input.txt); //
if (! inpf) {
cout << ;
return 1;
}
2
ofstream f;
f.open (output.txt, ios:: out); // open
if (!f) {
cout << ;
return 1;
}
, , .
. .
|
|
|
# include <fstream.h>
int main () {
char text [81], buf [81];
cout << ;
cin >> text;
ifstream f (text);
if (!f) {
cout << ;
return 1;
}
while (!f.eof ()) {
f.getline (buf,81);
cout << buf << endl;
}
return 0;
}
close (), , , .
-.
, , . :
istringstream ;
ostringstream ;
stringstream .
<sstream> istream, ostream iostream .
, , ++ ( string). . :
explicit istringstream (int mode = ios:: in);
explicit istringstream (const string & name, int mode = ios:: in);
explicit ostringstream (int mode = ios:: out);
explicit ostringstream (const string & name, int mode = ios:: out);
explicit stringstream (int mode = ios:: in | ios:: out);
explicit stringstream (const string & name, int mode = ios:: in | ios:: out);
explicit , .
str, :
string str () const;
void str (const string & S);
. , :
# include <sstream>
# include <string>
# include <iostream>
# include <ctime>
using namespace std;
string message (int i) {
ostringstream os;
time_t t;
time (&t); // time_t
os << time: << ctime (&t) <<number: << i << endl;
return os.str (); // ctime ()
//
}
int main () {
cout << message (22);
return 0;
}
++ . , -. , <string.h>.
() string , . , . <string>.
